Tubes or pipes are utilized in many environments for providing a conduit which may be used to deliver fluid flow or carry cables or wires, for instance. As an example, an irrigation network or system typically has a water source such as a water main or a well source with a pump for delivering water. Connected to the water source is one or more pipes for delivering water through the network, which may consist of a series of fluid-delivering arteries. Throughout the network, there is a number of pipes or tubes delivering water to sprinklers or other types of irrigation devices. Each of these tubes is coupled to each other, preferably with a generally leak-free connection.
Some of these connections are made by connecting threaded ends of the pipes to each other or to threaded couplings. Threaded joints present a number of deficiencies in use, such as being labor-intensive to connect. Threaded couplings also require full mating or seating of one member within another. This seating requires a certain degree of precision in sizing of pipes so that they span the proper distance. Nonetheless, threaded joints are prone to leaking, particularly as a result of deflection of one tube relative to the other which applies stress at the threads between the tubes. In order to improve the seal through threaded joints, the joints may be treated with pipe cement, or otherwise permanently joined, such as by welding. These methods tend to be messy, or labor-intensive, or both. Additionally, these methods are unreliable, and replacing a pipe or leaking coupling that has been welded or glued requires cutting out the joint and replacing the removed section, which itself may require re-threading fresh ends of the pipes and/or adding an additional pipe and coupling.
Frequently, the various tubes throughout the system lack a uniform diameter. That is, one tube may have a diameter of one size, while the tube to which it is to be joined has a diameter of a different size. This occurs for a number of reasons, such as consumers not recognizing the diametral difference when purchasing tubing, various manufacturers being partial to different tube gauges, or intentional variance to account for various flow rates through the fluid delivery system. Many couplings for joining pipes of different diameters merely make a step so that the coupling accommodates two specific tube sizes, thereby requiring a different coupling for each combination of possible tube sizes.
One concept for joining pipes or tubes that alleviates some of these issues is by using a joint coupling that includes at least two openings, each opening corresponding to a tube to be joined, wherein each opening includes a radial array of flexible or resiliently deformable members, such as a ring of fingers, for either sealing with or retaining a tube end within the coupling. One example of this concept is described in U.S. Pat. No. 6,231,909, to Fukao et al.
One problem with the fingered ring is the stiffness required. If the fingers are relatively soft, a tube may be easily inserted therein, and its position may easily be adjusted. However, a pressure surge through the tube and coupling may cause the tube to be expelled from the coupling. Alternatively, if the fingers are relatively stiff, such as if a metal ring is used with a radial array of barbed fingers, a pressure surge typically causes the fingers to bite into the tube. Unfortunately, these stiff fingers require greater work for receiving the tube and make adjusting the tube therein more difficult. Additionally, a coupling with stiffer materials does not tend to seal as well as a coupling where the fingered ring deforms more easily to compress against a seal.
Accordingly, there has been a need for an improved coupling device for connecting tubes, including tubes of different diametral sizes.